Marine craft supporting hydrofoil having depth controlling slots



1951 v J. A; JOHNSON 3,006,307

MARINE CRAFT SUPPORTING HYDRCFOIL HAVING I DEPTH CONTROLLING SLOTS Filed 001;. 12, 1960 2 Sheets-Sheet 1 INVENTOR. :h 71 A4905 Johnson BY 4. 74 e Oct. 31, 1961 J. A; JOHNSON MARINE CRAFT SUPPORTING HYDROFOIL HAVING DEPTH CONTROLLING SLOTS 2 Sheets-Sheet 2 Filed Oct. 12, 1960 INVENTOR. Jo/z AZ 02 Johrzsan W4 M AFORA/EX? Patented Oct. 31, 1951 3,006,307 MARINE CRAFT SUPPORTING HYDRC-FGKL HAVING DEPTH CONTROLLING SLGTS John Algot Johnson, 9 Sheridan Drive, Short Hills, NJ. Filed Oct. 12, 1960, Ser. No. 62,306 6 Claims. (Cl. 114-665) (Granted under Title 35, US. Code (1952 see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalties thereon.

The invention relates to marine craft or boats and more particularly to the type having submerged hydrofoils for supporting the hull of the boat out of the water.

In the past, difficulty has been encountered in maintaining the hydrofoils at the proper level of submersion throughout the full range of speeds. This normally required the full time and attention of an operator who would consequently be taken away from other duties.

In the prior devices which have dealt with this problem, the depth of submersion has been controlled by using water pressure responsive devices for changing the angle of the hydrofoil and thereby changing the lift. These devices have not proved sufficient for all purposes due to the inertia and friction in the linkage connecting the pressure responsive devices and the pivoted hy'drofoil portion.

The present invention obviates the aforementioned difficulties since the change in the lift is supplied by the water as it leaves a nozzle in the bottom of the hydrofoil. The present invention contemplates the control of the depth of submersion of the hydrofoil by the receipt of water through an opening in the hydrofoil support at a point which would correspond to the surface of the water when the hydrofoil is at the proper level of submersion. The water may be accelerated by a pump and passed through a nozzle in the bottom of the hydrofoil giving an increased lift to the hydrofoil.

It is therefore an object of the present invention to provide a device to maintain a constant depth of the hydrofoils over a wide range of boat speeds.

It is a further object to provide increased lift to a hydrofoil below a set depth of submersion and a decreased lift above said set depth.

It is a still further object to provide increased lift to a hydrofoil below a set depth of submersion and a decreased lift above said set depth sufiicient to maintain the hydrofoil at said set depth independently of the speed at which the hydrofoil moves through the water.

Other objects and many of the attendant advantages will become apparent and the invention will be better understood by reference to the following description and the accompanying drawings in which:

FIG. 1 is a view of the bottom of the boat embodying the present invention;

FIG. 2 is a detail of the nozzle in the hydrofoil;

FIG. 3 is a fragmentary sectional view of the hydrofoil shown in Fig. 1;

FIG. 4 is a fragmentary sectional View of the hydrofoil showing a modified position of the pump;

FIG. 5 is a fragmentary sectional View of the hy rofoil showing a further modified pump arrangement; and

FIG. 6 is a fragmentary perspective view showing portions of the drive for the pump shown in FIG. 5.

Referring now to FIGS. 1 through 3 of the drawing, a marine craft or boat 10 has a forwardly positioned or front supporting hydrofoil 11 and a rearwardly positioned or rear supporting hydrofoil 12. The hydrofoils 11 and 12 are disposed below the bottom of the boat 10 and perpendicular to a vertical plane which extends through the longitudinal center line of the boat and bisects the longitudinal extent of the hydrofoils.

The rear hydrofoil 12 it attached to the hull of the boat 10 by spaced apart, substantially vertical struts 13 and 14. The rear hydrofoil 12 may carry propellers 15 and 16, driven by a suitable engine (not shown) for the propulsion of the boat. The rear hydrofoil 12 does not require depth controlling devices since variations in the depth of the forward or front hydrofoil 11 Will change the angle of incidence of the rear hydrofoil and cause the rear hydrofoil to seek to maintain the boat on a substantially level keel at the current depth of the front hydrofoil.

The front hydrofoil 11 it attached to the hull of the boat 10 by spaced apart, substantially vertical, hollow struts 17 and'18 and an upwardly and forwardly inclined brace 19. The brace 19 extends from the mid-length location of hydrofoil 11 and the struts 17 and 18 extend from the hydrofoil at locations symmetrically positioned at respectively opposite sides of the brace 19.

A pair of longitudinally spaced apart and longitudinally extending slot openings 20 and 21 are provided in the bottom surface of hydrofoil 11. Mounted in the hydrofoil 11 is a slot wall formation or nozzle 22 having the discharge end mounted in the slots 20 or 21. The nozzle 22 has a throat opening 23 opposite the slot opening 20 or 21, which communicates with the interior of the corresponding strut 17 or 18. The slot openings 20 and 21 have an area that is no larger and which is preferably smaller than the area of the throat opening 23 so that water entering the nozzle 22 through the throat opening can be discharged as a high velocity jet from the slots 20 or 21. Guide vanes 22a are mounted in the nozzle 22 to guide the water from the throat opening 23 to the slot openings 20 or 21.

Water inlet openings 24 and 25 are provided in the forward edges of struts 17 and 18 respectively. These openings are located in such a position vertically that the openings 24 and 25 will be partly above and partly below the surface of the water when the hydrofoil 11 is supporting the bow of the boat 10 at the desired distance above the surface of the water. If the bow is too low, the openings 24 and 25 will be completely below the surface of the water and a large volume of water will flow through the openings and out of the slots 20 and 21 to increase the lift of the hydrofoil and raise the bow. If the bow is too high, a quantity of air will flow through the openings and be mixed with the water flowing from the slots 20 and 21 to decrease the lift of the hydrofoil 11 and lower the bow. Thusly, when the bow is at the proper distance above the surface of the water, the mixture of air and water is such as to maintain the lift of the hydrofoil 11 substantially constant. The hydrofoil 11 will therefore automatically seek the proper level to maintain the bow of the boat 10 at the predetermined distance above the surface of the water when the boat is under way.

While a certain amount of lift is applied to the hydrofoil 11 by the passage of water through nozzle 22 at all speeds of the boat 10, it is only at the higher speeds that such lift is of such magnitude as to maintain the bow of the boat at the proper distance above the surface of the water. To provide an adequate flow of water over a wide range of operating speeds, a pump 26 is mounted in each of the hollow struts 17 and 18. The pump 26 is secured in the struts by brackets 27 with an intake conduit 28 connecting the intake of the pump with the openings 24 or 25 and an outlet conduit 29 connecting the outlet of the pump with the throat opening 23 of the nozzle 22. A drive shaft 30 extends upwardly from the pump 26 through the hollow struts 17 or 18 and a bearing 31 in the bottom of the boat 10 to an angle drive 32. A shaft 33 extends from the angle drive 32 to an engine, not shown, to furnish the power for driving the pump 26.

In the modification shown in FIG. 4, the pump 26 is mounted substantially at the level of the water inlet opening 24 or 25 in the strut 17 or 18 with a short inlet conduit 34 leading from the opening 24 or 25 to the inlet of the pump and an elongated conduit 35 leading from the pump outlet to the throat opening 23 of the nozzle 22.

Referring to the modification shown in FIGS. and 6, the pump 26 is mounted in the strut 17 or 18 with its rotational axis horizontal instead of vertical. The pump is supported by brackets 36 and has a belt pulley 37 on one end of its shaft 38. An inlet conduit 39 leads fnom the inlet opening 24 or 25 to the inlet of the pump and an outlet conduit 40 leads from the outlet of the pump to the throat opening 23 of the nozzle 22.

A shaft 41 extends transversely of the boat above the upper ends of the struts 17 and 18 and is supported in bearings carried at the upper ends of vertically disposed stanchions or brackets 42, 43 and 44 mounted at their lower ends on the bottom or deck of the boat 10. The shaft 41 is driven by any suitable engine, not shown, through a shaft 45 and angle drive 46. Belt pulleys 47 and 48 are fixed to shaft 41 near its opposite ends and are connected to belt pulleys 67 on the pumps 26 in the struts 17 and 18 by belts 49 and 50.

In operation, as the boat moves, water is forced into the inlet of the pumps 26 through openings 24 and and inlet conduits 28. The water is pumped through the nozzles 22 by the pumps 26. The jet effect of the water passing through the nozzles 22 provides a lift to the hydrofoil 11 which is directly proportionate to the volume of water passing through the nozzles 22. Therefore, as the hull of boat 10 is lifted out of the water, the openings 24 and 25 will seek a position partly above and partly below the surface of the water where the hydrofoils, pump means having an inlet conduit connected to the Water receptionopenings and an outlet conduit connected to the water discharge openings, and nozzle means in said outlet conduit for providing a high velocity jet of water to provide increased lift to said one of the hydrofoils, the proportion of air to water in said jet of fluid and consequently the lift of said one hydrofoil being varied with changes in the operating depth of said one hydrofoil.

2. In a marine craft having a buoyant hull and hydrofoils for supporting the hull above the surface of the water at operating speeds of the craft wherein said hydrofoils comprise unitary members extending transversely of the hull one near the stern and one near the bow in fixed position relative to the hull and at least the bow hydrofoil is connected to the hull by spaced apart hollow struts of streamline cross sectional shape, and a brace disposed medially of the distance between the struts, means automatically controlling the operating depth of said hydrofoils when supporting said hull above the water comprising fluid outlet passages in the form of elongated narrow slots in the under surface of said bow hydrofoil disposed near the trailing edge of this hydrofoil and at respectively opposite sides of the mid-length location thereof, a fluid inlet passage in the leading edge of each of said hollow struts positioned to extend above and below the surface of the water when the hydrofoil is at the desired operating depth in the water, a nozzle structure connected between the fluid inlet passage in each hollow strut and the corresponding fluid outlet passage in said bow hydrofoil, vanes in each nozzle structure uniformly distributing the fluid received through the fluid 7 passage in said how hydrofoil, and a power driven fluid volume of water passing through the nozzles 22 will be just suflicient to maintain the hull of boat 10 at the proper distance above the surface of the water.

Without the pumps 26, the volume of water passing through the nozzles 22 wound depend upon the speed at which the boat 10 was moving. Through the use of the pumps 26, the volume of water passing through the nozzle 22 and hence the lift applied to the hydrofoil 11 can be controlled independently of the speed of the boat 10. The pumps 26 could be driven ata constant. speed which would give the same lift at all speeds of the boat or could be driven at a speed inversely proportionate to the speed of the boat 10. The latter arrangement would give the greater lift at slow speeds and a lesser lift at higher speed.

While the foregoing description and accompanying drawings are directed to a preferred illustrative embodiment of the instant invention and its manner of use, it will be understood that structural details may be modified to suit the invention to particular specific adaptations without departing from the spirit of the invention, and that, accordingly, it will be understood that it is intended and desired to embrace within the scope of the invention such modifications and changes as may be necessary or desirable to adapt it to varying conditions and uses as defined by the scope of the appended claims.

I claim:

1. In a boat having a hull adapted to be supported out of the water, a pair of submerged hydrofoils for supporting said hull, at least one pair of struts connecting each of said hydrofoils to said hull and means for controlling the depth of submersion of at least one of said hydrofoils, said means including water reception openings formed in the struts connecting said one of the hydrofoils to the hull and positioned to be partly above and partly below the surface of the water when the said one hydrofoil is at the desired operating depth, and water discharge openings formed in the bottom of said one of the pump connected with each nozzle structure to accelerate the fluid flowing through the nozzle structure from the fluid inlet passage in the corresponding strut to the corresponding fluid outlet passage in said bow hydrofoil to thereby augment the lift effect of the hydrofoil, the depth of submergence of said fluid inlet passages controlling the proportion of air to water in the fluid flowing through said nozzle structures and the proportion of air to water in said fluid directly aflecting the lift of said bow hydro- Y foil substantially at a constant operating depth.

. of the hull one near the stern and one near the bow in fixed position relative to the hull and at least the bow hydrofoil is connected to the hull by spaced apart hollow struts of streamline cross sectional shape, means automatically controlling the operating depth of said hydrofoils when supporting said hull above the water comprising fluid outlet passages in the form of elongated narrow slots in the under surface of said how hydrofoil disposed near the trailing edge of this hydrofoil and at respectively opposite sides of the mid-length location thereof, a fluid inlet passage in the leading edge of each of said hollow struts positioned to extend above and below the surface of the water when the hydrofoil is at the desired operating depth in the water, conduit means connected between the fluid inlet passage in each hollow strut and the corresponding fluid outlet passage in said bow hydrofoil, and power driven fluid pumps connected with said conduit means to accelerate the fluid flowing through the conduit means from the fluid inlet passages in said struts to the corresponding fluid outlet passages in said how hydrofoil to thereby augment the lift effect of the hydrofoil, the depth of submergence of said fluid inlet passages controlling the proportion of air to water in the fluid flowing through said fluid outlet passages and the proportion of air to water in said fluid directly affecting the lift of said bow hydrofoil to maintain the hydrofoil substantially at a constant operating depth.

4. In a marine craft having a buoyant hull and hydrofoils for supporting the hull above the surface of the water at operating speeds of the craft wherein said hydrofoils comprise unitary members extending transversely of the hull one near the stern and one near the bow in fixed position relative to the hull and at least the bow hydrofoil is connected to the hull by spaced apart hollow struts, means automatically controlling the operating depth of said hydrofoils when supporting said hull above the water comprising a fluid outlet passage in the form of at least one elongated narrow slot in the under surface of said bow hydrofoil disposed near the trailing edge of this hydrofoil, a fluid inlet passage in the leading edge of each of said hollow struts positioned to extend above and below the surface of the water when the hydrofoil is at the desired operating depth in the water, means including a power driven pump connecting the fluid inlet pasage in each hollow strut and the corresponding portion of the fluid outlet passage in said bow hydrofoil to accelerate the fluid flowing from the fluid inlet passage in the corresponding strut to the fluid outlet passage in said bow hydrofoil to thereby augment the lift efiect of the hydrofoil, the depth of submergence of said fluid inlet passages controlling the proportion of air to water in the fluid flowing from said fluid inlet passages to said fluid outlet passage and the proportion of air to water in said fluid directly aflecting the lift of said bow hydrofoil to maintain the hydrofoil substantially at a constant operating depth.

5. In a marine craft having a buoyant hull and hydrofoils for supporting the hull above the surface of the water at operating speeds of the craft wherein said hydrofoils comprise unitary members extending transversely of the hull one near the stern and one near the bow in fixed position relative to the hull and at least the b w hydrofoil is connected to the hull by spaced apart hollow struts, means automatically controlling the operating depth of said hydrofoils when supporting said hull above the water comprising fluid outlet passages in the form of elongated narrow slots in the under surface of said bow hydrofoil disposed near the trailing edge of this hydrofoil, a fluid inlet passage in the leading edge of each of said hollow struts positioned to extend above and below the surface of the water when the hydrofoil is at the desired operating depth in the water, conduit means connecting the fluid inlet passage in each hollow strut and the corresponding fluid outlet passage in said bow hydrofoil for the passage of fluid from the fluid inlet passage in the corresponding strut to and out of the fluid outlet passages in said bow hydrofoil to thereby augment the lift effect of the hydrofoil, the depth of submergence of said fluid inlet passages controlling the proportion of air to water in the fluid flowing through said struts and said hydrofoil and the proportion of air to water in said fluid directly affecting the lift of said bow hydrofoil to maintain the hydrofoil substantially at a constant operating depth.

6. In a marine craft having a buoyant hull and hydrofoils for supporting the hull above the surface of the water at operating speeds of the craft wherein said hydrofoils comprise unitary members extending transversely of the hull one near the stern and one near the bow in fixed position relative to the hull and at least one of said hydrofoils is connected to the hull by spaced apart hollow struts, means automatically controlling the operating depth of said hydrofoil when supporting said hull above the water comprising at least one fluid outlet passage in the form of an elongated narrow slot in the under surface of said one hydrofoil disposed near the trailing edge of this hydrofoil, a fluid inlet passage in the leading edge of each of said hollow struts positioned to extend above and below the surface of the Water when the hydrofoil is at the desired operating depth in the water, conduit means connecting the fluid inlet passage in each hollow strut and the fluid outlet passage in said one hydrofoil, and a power driven fluid pump connected with said conduit means to accelerate the fluid flowing through the conduit means from the fluid inlet passage in the corresponding strut to the fluid outlet passage in said one hydrofoil to thereby augment the lift effect of the hydrofoil, the depth of submergence of said fluid inlet passages controlling the proportion of air to water in the fluid flowing through said conduit means and the proportion of air to water in said fluid directly afiecting the lift of said one hydrofoil to maintain said one hydrofoil substantially at a constant operating depth.

References Cited in the file of this patent UNITED STATES PATENTS 2,709,979 Bush et al. June 7, 1955 2,764,954 Oeltgen Oct. 2, 1956 FOREIGN PATENTS 715,880 Great Britain Sept. 22, 1954 

